Hop alpha- and beta-acids are hop secondary metabolites whose application and function, till now, is well known in brewing, particularly of alpha-acids. In spite of their small and insufficient effect on productivity of dairy animals and also on milk quality, on the beginning of this century it was found the antibiotic effect of hop acids, because they decrease the population of gram-positive bacteria and protozoa in digestive track of ruminants. It is well known that higher population of gram-positive bacteria in animal feed and/or on pastures cause lower efficiency of animal feed and even infective diseases of digestive track. In these cases the most often therapy is antibiotic treatment with ionophores class of antibiotics. However, hop acids because of their specific chemical structure, have impact equal to ionophores and hop pellets could be added in hop feed in prevention. Apart from direct effect on decrease population of gram-positive bacteria, the emission of methane from animal waste is also decrease. Using of hops in feeding of ruminants has also a big economical importance, particularly from the aspect of organic dairy production, moreover, nowadays a non-clinical usage of antibiotic stimulators of animal growth in intensive cattle breeding is prohibited and on the other hand, researching of alternative matters (probiotics, prebiotics and immunomodulators) and their application as additives in animal feed has been increased. However, big hop surplus on the world market; hops and hop pellets are more accessible than ever.
The objective of the present study was to determine the effect of different sources of dietary fibre on the oxidative stress induced by a high fat diet in laboratory rats. Thirty two laboratory rats were penned individually and divided into four groups: CONT (high fat diet), G(70 g guar gum/kg), P(70 g apple pectin/kg) and WB(155 g wheat/kg). After 11 or 13 days of treatment DNA damage of blood leukocytes was measured by Comet assay and lipid peroxidation was studied by determining the malondialdehyde (MDA) concentration in liver and in urine. All three studied groups showed reduced liver MDA concentrations but only group WB was significant compared to group CONT. In comparison with group CONT, the groups WB and P had significantly reduced 24-hour urine MDA excretion, but not group G. The results of the experiment confirmed that wheat bran intake effectively reduces oxidative stress induced by a high fat diet.
Farm animals in intensive farming systems are frequently exposed to oxidative stress, which demands adequate antioxidant protection. The results from this study show that, besides being known as antimicrobial and antiviral agent, Sweet chestnut wood extract could also be considered as a promising natural antioxidant in animal nutrition.